add comment in cloud interface

add comment in cloud interface

Change-Id: I079cdecf04cf3f8739d804ff6f26317fbbcd47fc
Signed-off-by: Jung Seungho <shonest.jung@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12391
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jee Hyeok Kim <jihyeok13.kim@samsung.com>
(cherry picked from commit 1e4047c5a89db80e19be42eb076c253d6828530a)
Reviewed-on: https://gerrit.iotivity.org/gerrit/15273
Reviewed-by: George Nash <george.nash@intel.com>
Reviewed-by: Phil Coval <philippe.coval@osg.samsung.com>